1. Field of the Invention
The present invention relates generally to fastening devices and, more particularly, to a swivel hoist ring for being removably connected to trench plates.
2. Description of Related Art
Various swivel hoist rings have been implemented in the prior art. U.S. Pat. No. 3,297,293 to Andrews et al. discloses a fastening device comprising an eye member which is pivotally and rotationally mounted onto a base. The fastening device, however, comprises a relatively small-diameter retaining ring for contacting the base. Horizontal forces exerted onto the fastening device must thus be absorbed by a stud secured into the base and the relatively small-diameter retaining ring. Additionally, removal of the fastening device from the base can only be achieved by using a tool to grip the head of the stud, which is also configured to have a relatively small diameter. If the head of the stud is damaged, or if a wrench is not available for fitting onto the head of the stud, then the fastening device cannot easily be removed.
Trench plates generally comprise rectangular steel members weighing between 5,000 and 9,000 pounds. A typical trench plate may be 8 feet wide by 12 feet long and 2 inches thick. A threaded nut is secured in a middle area of the trench plate, and is adapted for receiving an eye bolt, according to the prior art. The eye bolt comprises an opening, for receiving a cable or other fastening member. Once the eye bolt is threaded into the nut of the trench plate, and is fastened to a cable, for example, the trench plate can be removed. Eye bolts, however, are incapable of swiveling and maintaining structural integrity under off-axis horizontal loads.
The trench plate connector of the present invention comprises a large-diameter skirt member for dissipating lateral forces applied onto the trench plate connector. The large-diameter skirt member is threaded onto a stud, and can be locked onto the stud with a nut. Once the large-diameter skirt member is locked into place, one or more arms of the large-diameter skirt member can be used to apply rotational forces onto the trench plate connector to thereby secure or remove the stud of the trench plate connector from the trench plate. Each arm of the large-diameter skirt member can be impact ed with a hammer, for example, to apply substantial rotational forces onto the trench plate connector for tightening or removal thereof. A unique double-threaded stud is used to accommodate the large-diameter skirt member of the present invention. The double-threaded stud comprises a first thread on one end for being threaded into a trench plate, and a second thread on the other end for accommodating both the large-diameter skirt member and a securing nut.